docs: def create_user(username, password, **kwargs):
      """
      return flag, result(result can be an User object or just True, {} for errors)
      """
      try:
          User = get_model('user')
          user = User.get(User.c.username==username)
          if user:
              return False, {'username':"Username is already existed!"}
          user = User(username=username, password=password, **kwargs)
          user.set_password(password)
          user.save()
          return True, user
      except Exception as e:
          log.exception(e)
          return False, {'_': "Creating user failed!"}